Structural and Electrochemical Studies on Lithium Manganese Oxide Containing Li + Prepared by Hydrothermal Method for Lithium Ion Batteries

Abstract

利 用 X R D、 I C P、 T G A 、 D T A 及 恒 流 充 放 电 等 方 法 研 究 分 析 了 一 种 特 殊 天 然 结 构 Mn O2( N M D) 材料的结 构、组成 以及电 化学嵌锂 特性. X R D 分析 表明,该样 品材料 是由钠水 锰矿以及水羟 锰矿复 合结构组 成的 Mn O2 纳米 纤 维. 充放 电 循环 结果 显 示,其 前 期循 环容 量 可高 达 150m Ah/ g 左 右,但性 能尚不够 稳定. 本文采 用一种 水热法高 压嵌锂处 理,可将 N M D 样品 转变为 具有3 ×3 大隧道结 构的钡 镁锰矿( Todorokite) 型锂 锰氧 化 物,既 增 强了 Li + 嵌 入 隧道 或 层间 结 构 的循环稳定 性. 并 显著提 高锂锰氧 化物电 极材料性 能的 稳定 性,以 充放 电电 流密 度 为0 .8 m A/c m 2 ,经过180 次 循环后 其比容量 仍具有 110 m Ah/ g . 该类 大隧道结 构锂锰 氧化物可 作为一 种3 V 的锂离子电极 材料.In this paper, Todorokite manganese oxides containing Li + with large tunnel structure(sample M5) have been synthesized by hydrothermal methods from natural manganese oxide nano fiber (sample M4). The structure and composition of the samples were characterized and analyzed by XRD, ICP, TGA and DTA. Its electrochemical behavior as a cathode materials for rechargeable lithium ion insertion were studied by galvanostatic charge/discharge measurements. XRD results show that the sample M4 is mainly composed of Birnessite and Vernadite structure. Although the sample M4 shows a high initial capacity of approximately 150 mAh/g, its performances decrease gradually over 30 cycles. It is found that the materials have highly reversible charge/discharge cycling performances after being converted into Todorokite lithium manganese oxide(sample M5). This sample exhibit a single reduction step centered at Ca. 2.8 V and its discharge capacity maintains about 110 mAh/g after 180 cycles at current density of 0.8 mA/cm 2. The novel lithium manganese oxide with a large tunnel structure can be used as 3V cathode material of lithium ion batteries.作者联系地址:厦门大学固体表面物理化学国家重点实验室!厦门大学物理化学研究所化学系厦门361005,厦门大学固体表面物理化学国家重点实验室!厦门大学物理化学研究所化学系厦门361005,厦门大学固体表面物理化学国家重点实验室!厦门大学物理化学研究所化学系厦门361005,厦门大学固体表面物理Author's Address: State Key Lab. for Phys. Chem. of Solid Surf., Inst. of Phys. Chem., Dept. of Chem., Xiamen Univ., Xiamen, 36100

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